U.S. patent application number 14/781171 was filed with the patent office on 2016-11-10 for catalyst for the synthesis of methyl mercaptan and process for producing methyl mercaptan from synthesis gas and hydrogen sulphide.
This patent application is currently assigned to Arkema France. The applicant listed for this patent is ARKEMA FRANCE. Invention is credited to Patrice BARRE, Pascal BLANCHARD, Alexia CORDOVA, Georges FREMY, Carole LAMONIER, Karine SANCHOU.
Application Number | 20160326105 14/781171 |
Document ID | / |
Family ID | 48741374 |
Filed Date | 2016-11-10 |
United States Patent
Application |
20160326105 |
Kind Code |
A1 |
FREMY; Georges ; et
al. |
November 10, 2016 |
CATALYST FOR THE SYNTHESIS OF METHYL MERCAPTAN AND PROCESS FOR
PRODUCING METHYL MERCAPTAN FROM SYNTHESIS GAS AND HYDROGEN
SULPHIDE
Abstract
The invention relates to a catalyst comprising an active
component based on molybdenum and on potassium and a support based
on hydroxyapatite, and also to a process for preparing said
catalyst and a process for producing methyl mercaptan in a
catalytic process by reaction of carbon monoxide, sulphur and/or
hydrogen sulphide and hydrogen, comprising the use of said
catalyst.
Inventors: |
FREMY; Georges; (Sauveterre
De Bearn, FR) ; BARRE; Patrice; (Lons, FR) ;
SANCHOU; Karine; (Pau, FR) ; CORDOVA; Alexia;
(Lille, FR) ; LAMONIER; Carole; (Armentieres,
FR) ; BLANCHARD; Pascal; (Lens, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ARKEMA FRANCE |
Colombes |
|
FR |
|
|
Assignee: |
Arkema France
Colombes
FR
|
Family ID: |
48741374 |
Appl. No.: |
14/781171 |
Filed: |
March 28, 2014 |
PCT Filed: |
March 28, 2014 |
PCT NO: |
PCT/EP2014/056343 |
371 Date: |
September 29, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C07C 319/06 20130101;
B01J 35/0006 20130101; B01J 37/0201 20130101; B01J 27/051 20130101;
B01J 27/1806 20130101; B01J 37/0207 20130101; B01J 23/745 20130101;
C07C 321/04 20130101; C07C 319/02 20130101; B01J 23/28 20130101;
B01J 23/755 20130101; B01J 35/1014 20130101; B01J 27/0576 20130101;
C07C 319/02 20130101 |
International
Class: |
C07C 319/02 20060101
C07C319/02; B01J 23/28 20060101 B01J023/28; B01J 27/18 20060101
B01J027/18; B01J 35/00 20060101 B01J035/00; C07C 319/06 20060101
C07C319/06; B01J 27/057 20060101 B01J027/057; B01J 23/755 20060101
B01J023/755; B01J 23/745 20060101 B01J023/745; B01J 37/02 20060101
B01J037/02; B01J 27/051 20060101 B01J027/051; B01J 35/10 20060101
B01J035/10 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2013 |
FR |
1352871 |
Claims
1. A catalyst comprising a molybdenum- and potassium-based active
component and a hydroxyapatite-based support.
2. The catalyst as claimed in claim 1, wherein the catalyst support
is hydroxyapatite having stoichiometric formula
Ca.sub.10(PO.sub.4).sub.6(OH).sub.2.
3. The catalyst as claimed in claim 1, wherein the molybdenum- and
potassium-based active component is selected from the group
consisting of compounds based on Mo--S--K, compounds based on
Mo--O--K, and their mixtures.
4. The catalyst as claimed in claim 3, wherein the molybdenum- and
potassium-based active component has been obtained from a precursor
having structure K.sub.2MoS.sub.4.
5. The catalyst as claimed in claim 4, wherein the weight ratio of
K.sub.2MoS.sub.4 and Ca.sub.10(PO.sub.4).sub.6(OH).sub.2 used to
obtain the catalyst is
K.sub.2MoS.sub.4/Ca.sub.10(PO.sub.4).sub.6(OH).sub.2=31.3/100
6. The catalyst as claimed in claim 3, wherein the molybdenum- and
potassium-based active component has been obtained from a precursor
having structure K.sub.2MoO.sub.4.
7. The catalyst as claimed in claim 6, wherein the weight ratio of
K.sub.2MoO.sub.4 and Ca.sub.10(PO.sub.4).sub.6(OH).sub.2 used to
obtain the catalyst is:
K.sub.2MoO.sub.4/Ca.sub.10(PO.sub.4).sub.6(OH).sub.2=50.7/100
8. A preparation process for the catalyst as defined in claim 1,
comprising the following steps: preparing a precursor for the
molybdenum- and potassium-based active component; preparing the
hydroxyapatite-based support; and dry impregnating the
hydroxyapatite-based support with the precursor for the molybdenum-
and potassium-based active component.
9. A process for producing methyl mercaptan in a catalytic process
by reacting carbon oxide, sulfur and/or hydrogen sulfide and
hydrogen, comprising using a catalyst as defined in claim 1.
10. A method for preparing a catalyst useful for producing methyl
mercaptan, comprising using hydroxyapatite as a support for
preparing the catalyst.
11. The catalyst as claimed in claim 1, wherein the hydroxyapatite
of the hydroxyapatite-based support has a Ca/P molar ratio ranging
from 1.5 to 2.1.
12. The catalyst as claimed in claim 1, wherein the hydroxyapatite
of the hydroxyapatite-based support has a Ca/P molar ratio of
1.67.
13. The catalyst as claimed in claim 1, wherein the
hydroxyapatite-based support has a specific area greater than 25
m.sup.2/g.
14. The catalyst as claimed in claim 1, wherein the
hydroxyapatite-based support has a specific area greater than 40
m.sup.2/g.
15. The catalyst as claimed in claim 1, additionally comprising a
promoter.
16. The catalyst as claimed in claim 15, wherein the promoter is
selected from the group consisting of tellurium oxide, nickel oxide
and iron oxide.
Description
[0001] The work that led to this invention received financing from
the European Union as part of the 7th Framework Programme
(FP7/2007-2013) under project number No. 241718 EUROBIOREF.
[0002] The present invention relates to a specific molybdenum- and
potassium-based catalyst that is useful for producing methyl
mercaptan from synthesis gas and hydrogen sulfide, and to its
preparation process.
[0003] The invention also relates to a process for producing methyl
mercaptan that uses this catalyst.
[0004] The invention lastly relates to the use of hydroxyapatite as
a support for a catalyst for producing methyl mercaptan.
[0005] Methyl mercaptan has great industrial interest, particularly
as a raw material for synthesizing methionine, an essential amino
acid that is in widespread use in animal food. Methyl mercaptan is
also a raw material for many other molecules, in particular
dimethyldisulfide (DMDS), a sulfidation additive for hydrotreating
catalysts in petroleum fractions, among other applications.
[0006] Methyl mercaptan is commonly produced in large tonnages
industrially from methanol and hydrogen sulfide. It may prove
economically interesting to want to produce methyl mercaptan
directly from carbon monoxide, hydrogen and hydrogen sulfide
according to the following reaction scheme:
CO+2H.sub.2+H.sub.2S.fwdarw.CH.sub.3SH+H.sub.2O (1)
[0007] The main by-product from this synthesis is carbon dioxide.
Carbonyl sulfide (COS) is considered to be the reaction
intermediate, which leads to methyl mercaptan after hydrogenation
according to the following reaction schemes:
CO+H.sub.2S.fwdarw.COS+H.sub.2 (2)
COS+3H.sub.2.fwdarw.CH.sub.3SH+H.sub.2O (3)
[0008] The carbon dioxide comes from two side reactions:
CO+H.sub.2O=CO.sub.2+H.sub.2 (4)
and
COS+H.sub.2O.fwdarw.CO.sub.2H.sub.2S (5)
[0009] These two side reactions, which consume the main raw
material: carbon monoxide, and the reaction intermediate: carbonyl
sulfide, are due to the inescapable presence of water, coproduced
during methyl mercaptan synthesis. The carbon dioxide can
optionally be recycled to produce methyl mercaptan as well
according to the following scheme:
CO.sub.2+3H.sub.2+H.sub.2S.fwdarw.CH.sub.3SH+2H.sub.2O (6)
[0010] But this reaction is known to be slower than that from
carbon monoxide. Therefore there is incentive to make carbon
dioxide production as low as possible at the outlet of the methyl
mercaptan reactor.
[0011] From document WO2005/040082 several catalysts are known for
the synthesis of methyl mercaptan from synthesis gas and hydrogen
sulfide.
[0012] In particular, this document discloses the use of a catalyst
comprising a Mo--O--K based active component, an active promoter
and optionally a support. The catalysts exemplified have different
chemical natures, such as K.sub.2Mo.sub.4/Fe.sub.2O.sub.3NiO or
K.sub.2MoO.sub.4/CoO/CeO.sub.2/SiO.sub.2, each supported on silica.
This leads to a CO.sub.2/MeSH selectivity ratio of 0.88 at
333.degree. C.
[0013] A family of catalysts composed of a porous support onto
which a metal has been deposited electrolytically is also known
from document US2010/0286448. K.sub.2MoO.sub.4 and another metal
oxide as promoter were then impregnated onto this support. Example
15 of this document describes the preparation of
K.sub.2MoO.sub.4/NiO/CoSiO.sub.2. The CO.sub.2/MeSH selectivity
ratio with this complex catalyst is 0.65.
[0014] Lastly, US document 2010/0094059 describes supported
K.sub.2MoO.sub.4 based catalysts, where the porous support used
alone or in mixtures is chosen from SiO.sub.2, Al.sub.2O.sub.3,
TiO.sub.2, Al.sub.2O.sub.3/SiO.sub.2, ZrO.sub.2, zeolites or
carbon-containing materials. Tellurium oxide (TeO.sub.2) is used as
promoter. The CO.sub.2/MeSH selectivity ratios are comprised
between 0.60 and 0.77 measured at 300.degree. C.
[0015] From the teaching of these documents it has been observed
that combining catalysts with specific structures, promoters and
supports, each being carefully selected, means that interesting
selectivity ratios can be achieved.
[0016] There is a current need for a catalyst that is simply
synthesized and leads to very good selectivity. This technical
problem has been resolved by a molybdenum- and potassium-based
catalyst supported by hydroxyapatite.
[0017] It has been observed that the catalyst according to the
invention is easier to prepare, given that the presence of a
promoter is not indispensable. It is less costly than those
disclosed in the previously cited documents. And lastly, it leads
to very good CO.sub.2/MeSH selectivities.
[0018] The invention also relates to the preparation process for
this catalyst.
[0019] The invention also relates to a process for producing methyl
mercaptan from synthesis gas and hydrogen sulfide using the
catalyst according to the invention.
[0020] The invention also relates to the use of the catalyst as
defined above for the synthesis of methyl mercaptan from synthesis
gas and hydrogen sulfide.
[0021] Lastly the invention relates to the use of hydroxyapatite as
support for preparing a catalyst for producing methyl mercaptan,
and in particular in a catalytic process by reacting carbon oxide,
sulfur and/or hydrogen sulfide and hydrogen.
[0022] Other characteristics, features, subjects and benefits of
the present invention will emerge even more clearly on reading the
description and the examples that follow.
[0023] Any range of values denoted by the expression "between a and
b" represents the values ranging from more than a to less than b
(i.e. limits a and b excluded), while any range of values denoted
by the expression "from a to b" means the values ranging from a to
b (i.e. including the limits a and b).
[0024] Catalyst
[0025] The present invention relates to a catalyst.
[0026] This catalyst comprises a molybdenum- and potassium-based
active component and a hydroxyapatite-based support.
[0027] Active Component
[0028] The active component present in the catalyst according to
the invention comprises molybdenum and potassium within a single
component.
[0029] Preferably, the molybdenum- and potassium-based active
component is chosen from compounds based on Mo--S--K, compounds
based on Mo--O--K, and their mixtures.
[0030] The Mo--S--K based active component may be obtained by
deposit and calcination of K.sub.2MoS.sub.4 or (NH.sub.4).sub.2
MoS.sub.4 precursors with impregnated K.sub.2CO.sub.3 added
separately to the support.
[0031] The Mo--O--K based active component may be obtained by
deposit and calcination of K.sub.2MoO.sub.4 or (NH.sub.4).sub.2
MoO.sub.4 precursors with impregnated K.sub.2CO.sub.3 added
separately to the support.
[0032] it is also possible to use ammonium heptamolybdate
(NH.sub.4).sub.6Mo.sub.7O.sub.24.4H.sub.2O as reagent, in the
presence of a potassium salt such as for instance potassium nitrate
KNO.sub.3, potassium carbonate K.sub.2CO.sub.3 or potassium
hydroxide KOH.
[0033] These compounds are precursors of Mo--S--K and Mo--O--K
based active phases respectively. The active phases are obtained
after in situ precursor pretreatment, with for example a procedure
consisting in a first step of drying in nitrogen at 250.degree. C.,
followed by sulfidation with hydrogen sulfide at the same
temperature for 1 hour, then a step of reduction/sulfidation with
H.sub.2/H.sub.2S at 350.degree. C. for 1 hour.
[0034] Support
[0035] The catalyst support according to the invention is
hydroxyapatite having formula Ca.sub.10(PO.sub.4).sub.6(OH).sub.2,
advantageously a stoichiometric hydroxyapatite.
[0036] Preferably, hydroxyapatite that is useful according to the
present invention has a Ca/P molar ratio ranging from 1.5 to 2.1,
and more preferably 1.67, corresponding to the expected value for
stoichiometric hydroxyapatite.
[0037] Preferably, the weight ratio of the catalyst according to
the invention is:
K.sub.2MoS.sub.4/Ca.sub.10(PO.sub.4).sub.6(OH).sub.2=31.3/100
K.sub.2MoO.sub.4/Ca.sub.10(PO.sub.4).sub.6(OH).sub.2=50.7/100
[0038] The catalytic activity may be improved by using a support
material having a specific area greater than 25 m.sup.2/g.
[0039] Preferably, the hydroxyapatite supports according to the
invention have a specific area of at least 40 m.sup.2/g, more
specifically the specific area ranges from 40 m.sup.2/g to 300
m.sup.2/g and a Ca/P molar ratio of 1.67.
[0040] The structure of the support may be three dimensional,
spherical, cylindrical, ring-shaped, star-shaped, granulates or any
other three dimensional shape, or in the form of a powder, which
can be pressed, extruded, granulated or in a three dimensional
shape.
[0041] Preferably, the catalyst particles have uniform particle
size distribution with diameter from 0.1 mm to 20.0 mm measured by
sieve analysis.
[0042] Promoter
[0043] Preferably, the catalyst according to the invention consists
in a molybdenum- and potassium-based active component and a
hydroxyapatite-based support.
[0044] However, it is possible to envisage the presence of a
promoter known to the person skilled in the art, such as tellurium
oxide, nickel oxide or iron oxide.
[0045] Catalyst Preparation Process
[0046] The invention also relates to the preparation process for
the catalyst according to the invention. This process comprises the
following successive steps: [0047] preparing the precursor for the
active phase [0048] preparing the support, and [0049] dry
impregnating the support with the active phase precursor.
[0050] Preparing the Precursor for the Active Phase
[0051] 1/Mo--O--K
[0052] 1. The K.sub.2MoO.sub.4 salt is a commercial salt. To
prepare the Mo--O--K based-catalyst, a fixed quantity of
K.sub.2MoO.sub.4 is dissolved in a volume of water to obtain a
solution with desired concentration, such as for example a
concentration ranging from 0.5-1.0 g/mL.
[0053] 2. It is also possible to begin with separated molybdenum
and potassium salts, i.e. that are not part of the same compound.
For this synthesis, a molybdenum-based solution is prepared by
adding ammonium heptamolybdate in water to obtain a MoO.sub.3
concentration ranging from 22 to 33% by weight.
[0054] In parallel, a potassium-based solution is prepared by
adding potassium nitrate in water to obtain a K.sub.2O
concentration ranging from 31 to 43% by weight.
[0055] 2/Mo--S--K
[0056] The K.sub.2MoS.sub.4 synthesis is generally done in two
steps.
[0057] The first step involves preparing ammonium
tetrathiomolybdate (ATTM); the second step is the synthesis of
potassium tetrathiomolybdate (K.sub.2MoS.sub.4) from the salt
prepared in the first step.
[0058] To prepare ATTM, hydrogen sulfide is left to bubble
continuously in a 25% aqueous ammonia solution, in which ammonium
heptamolybdate (HMA) has been dissolved. The solution temperature
increases, indicating an exothermic reaction. The hydrogen sulfide
bubbling is stopped when the temperature falls (generally after one
hour).
[0059] The solution then contains red crystals with green
reflections, which correspond to ammonium tetrathiomolybdate.
[0060] The second step consists in an ion exchange between ammonium
ions in the ammonium tetrathiomolybdate salt obtained and potassium
ions, which come from a potassium hydroxide solution. The salts
obtained are then stored under vacuum. A quantity of potassium
tetrathiomolybdate is dissolved in water.
[0061] The potassium salt useful in the catalyst according to the
present invention may come from the following compounds: potassium
acetate (KAc), potassium oxalate (K.sub.2C.sub.2O.sub.4), potassium
hydroxide (KOH), potassium carbonate (K.sub.2CO.sub.3), potassium
nitrate (KNO.sub.3), and potassium bicarbonate (KHCO.sub.3).
[0062] Support Preparation
[0063] The catalyst support, constituted of hydroxyapatite, is
prepared by a coprecipitation method. An aqueous solution of
calcium nitrate Ca(NO.sub.3).sub.2 was added dropwise to an
ammonium hydrogenphosphate (NH.sub.4)H.sub.2PO.sub.4 solution with
stirring. The temperature is held at 100.degree. C. and the pH is
held at 10 with addition of an ammonia solution (25%).
[0064] The resulting white precipitate is filtered, washed, dried
at 80.degree. C. overnight and calcinated at 400.degree. C. The
hydroxyapatite Ca.sub.10(PO.sub.4).sub.6(OH).sub.2 was obtained
with a Ca/P molar ratio of 1.67 corresponding to the expected value
for a stoichiometric hydroxyapatite.
[0065] Dry Impregnating the Support with the Active Phase
Precursor
[0066] 1/Mo--O--K
[0067] The dry impregnation method is used to prepare the catalyst.
The K.sub.2MoO.sub.4 solution is impregnated in one step on the
support. When the solutions containing potassium and molybdenum are
distinct, the impregnation is done in 2 steps.
[0068] 2/Mo--S--K
[0069] A potassium tetrathiomolybdate solution is then impregnated
onto hydroxyapatite. The molybdate content in the catalyst depends
on the K.sub.2MoS.sub.4 or K.sub.2MoO.sub.4 solubility and the
support's porous volume.
[0070] The K.sub.2MoS.sub.4 solubility is between 0.25 g/mL and
0.50 g/mL (0.35 g/mL) and the K.sub.2MoO.sub.4 solubility is
between 0.50 g/mL and 1.50 g/mL (0.90 g/mL). The support's porous
volume is between 0.8 mL/g and 2.2 mL/g.
[0071] Consequently, the volume of solution used is calculated to
obtain the desired weight ratio, and preferably the weight ratio as
defined above.
[0072] After impregnation, the solid undergoes a maturation step
for 2 hours, then oven drying at 80.degree. C. for 24 hours, and
calcination under gas flow (typically air) at 490.degree. C. for 4
hours. If a second impregnation step is necessary, the solid
undergoes the maturation, drying and calcination steps again.
[0073] Production Process for Methyl Mercaptan
[0074] The invention relates to a production process for methyl
mercaptan in a catalytic process by reacting carbon oxide, sulfur
and/or hydrogen sulfide and hydrogen, comprising the use of a
catalyst as defined above.
[0075] The CO or CO.sub.2/H.sub.2S/H.sub.2 molar ratios range from
1/1/0 to 1/8/8, or when sulfur is used to replace hydrogen sulfide,
the molar ratios of CO or CO.sub.2/H.sub.2S/H.sub.2/S reagents
range from 1/1/0/1 to 1/8/8/8.
[0076] Preferably, the CO or CO.sub.2/H.sub.2S/H.sub.2 molar ratios
range from 1/2/1 to 1/4/4, when sulfur is used to replace hydrogen
sulfide, the molar ratios of CO or CO.sub.2/H.sub.2S/H.sub.2/S
reagents from 1/2/2/1 to 1/4/4/4.
[0077] These molar ratios take CO.sub.2 into account. Therefore,
they consider both reaction scheme (1) and reaction scheme (6).
[0078] Preferably, the reaction may occur in fixed tubular,
multitubular, catalytic wall micro-channel or fluid bed
reactors.
[0079] The invention also relates to the use of the catalyst as
defined above for the production of methyl mercaptan from synthesis
gas and hydrogen sulfide.
[0080] Lastly the invention relates to the use of hydroxyapatite as
support for preparing a catalyst for producing methyl mercaptan,
and in particular in a catalytic process by reacting carbon oxide,
sulfur and/or hydrogen sulfide and hydrogen.
[0081] The present invention will now be described in the examples
below, these examples being given only for illustration, and are of
course not limiting.
EXAMPLES
Example 1
[0082] The catalyst according to the invention is prepared
according to the dry impregnation method, as defined above.
[0083] The resulting catalyst has the following
characteristics:
TABLE-US-00001 TABLE 1 Elemental analysis of the catalyst Catalyst
Chemical composition (% by weight) Mo K S N K.sub.2MoS.sub.4/Hap
9.9 8.1 13.3 <0.10
Example 2
[0084] The catalyst used is K.sub.2MoO.sub.4 on hydroxyapatite
Example 3
[0085] The catalyst tested is K.sub.2MoO.sub.4 on SiO.sub.2
Example 4
[0086] The catalyst tested is K.sub.2MoS.sub.4 on
Al.sub.2O.sub.3
Example 5
[0087] The catalyst tested is K.sub.2MoO.sub.4 on
Al.sub.2O.sub.3.
Evaluating the Catalysts
[0088] The catalysts are evaluated in a reaction to produce methyl
mercaptan in a fixed-bed reactor in the following conditions:
[0089] Temperature: 280.degree. C.,
[0090] Pressure: 10 bars,
[0091] Composition of CO/H.sub.2/H.sub.2S=1/2/1 feed gas (v/v),
[0092] GHSV (Gas Hourly Space Velocity)=1333 h.sup.-1
[0093] The reagents and products were analyzed in-line by gas
chromatography.
[0094] Before the test, the catalysts were activated in situ with a
first procedure consisting in a first step of drying in nitrogen at
250.degree. C., followed by sulfidation with hydrogen sulfide at
the same temperature for 1 hour, then a step of
reduction/sulfidation with H.sub.2/H.sub.2S at 350.degree. C. for 1
hour.
[0095] The results are in table 2 below.
TABLE-US-00002 TABLE 2 Results of catalytic tests Molar
selectivities (%) Examples Catalyst CH.sub.3SH COS CO.sub.2
CO.sub.2/CH.sub.3SH ratio 1 (inv) K.sub.2MoS.sub.4/Hap 44.1 23.3
32.6 0.74 2 (inv) K.sub.2MoO.sub.4/Hap 43.3 23.6 31.9 0.74 3 (comp)
K.sub.2MoO.sub.4/SiO.sub.2 48.8 5.3 45.3 0.93 4 (comp)
K.sub.2MoS.sub.4/Al.sub.2O.sub.3 45.0 7.3 46.6 1.04 5 (comp)
K.sub.2MoO.sub.4/Al.sub.2O.sub.3 47.0 3.4 49.6 1.06
[0096] The results presented in table 2 show that the catalysts
according to the invention (examples 1 and 2) give much lower
CO.sub.2 (undesired product) selectivities than catalysts on the
supports in the prior art (silica: example 3 or alumina: examples 4
and 5).
[0097] The selectivities are compared using carbon monoxide
isoconversion, where this conversion is expressed by m.sup.2 of
specific air in the catalyst.
[0098] By comparing the results obtained with catalysts 1 and 4, we
observe a 30% improvement in ratio, and this improvement is linked
to choosing hydroxyapatite as support.
[0099] The same observation is seen when comparing example 2
according to the invention and examples 3 and 5.
[0100] We observe increased methyl mercaptan selectivity compared
to the carbon dioxide produced according to a side reaction.
[0101] It should be noted that this selectivity is obtained without
aid from the promoter such as tellurium oxide, nickel oxide or iron
oxide as described in the prior art.
* * * * *